// import '@babel/polyfill'
let a = 1
let b = 1
if (a == b) {
    console.log(1)
}
 function aa() { 
    new Promise((reslove,reject) => { 
        reslove(1)
    })
}
new aa()
console.log(Array.from(new Set([1, 2, 3, 2, 1])))